This proposal describes the preparation and evaluation of new gene delivery vehicles composed of dendritic amphiphiles and DMA. These new functional dendritic amphiphiles undergo an electrostatic transition from cationic to anionic via an esterase-catalyzed reaction intracellularly to release DMA from the nanoscale assembly. We hypothesize that this change in electrostatic interactions with DNA will lead to increased gene transfection levels. A detailed, systematic investigation is proposed that entails the following three specific aims for this three-year R21 proposal: Aim 1. Determine the key molecular characteristics of the dendritic amphiphile required for binding and release of DNA. Aim 2. Characterize the nanoscale assemblies formed with the dendritic amphiphiles, and dendritic amphiphiles and DNA. Aim 3. Evaluate functional interactions of dendritic amphiphile/DNA assemblies with cells in vitro and deliver the p53 gene to colon cancer cells. The results of successful completion of this study will be: 1) one or more functional dendritic amphiphiles for delivery of the p53 gene to colon cancer cells; 2) a database of structure-property relationships; and 3) insight into the design of optimized dendritic vectors. These studies will also provide detailed physicochemical and biological information on this new class of dendritic amphiphiles and their corresponding assemblies, which is key for the future development of functional dendrimer/DNA assemblies for gene delivery. Relevance to Public Health: Innovative strategies to treat or cure colon cancer are still needed. Today, the current treatment protocols have resulted in improved patient care but the response rate remains only about 35% for metastatic colon cancer patients. In this proposal new well-defined polymers are described for the delivery of a tumor suppressor gene for the treatment of colon cancer.